1. Technical Field
The present invention relates to a low noise wide band amplifier and more particularly to a low noise wide bandwidth amplifier with an active load input matching network which eliminates the need for relatively large reactive elements, such as inductors and capacitors, in order to minimize the amplifier layout area.
2. Description of the Prior Art
Distributed amplifiers are known to be used for relatively wide bandwidth applications. Examples of such distributed amplifiers are disclosed in U.S. Pat. Nos. 4,992,752; 5,361,038; 5,550,513; 5,559,472; 5,751,190; 5,920,230 and 6,094,099. Such distributed amplifiers are also well documented in the literature: “A 74 GHz Bandwidth InAlAs/InGaAs-InP HBT Distributed Amplifier with a 13-dB Gain” by Baeyens, et al. IEEE Microwave and Guided and Wave letters, Vol. 9, Issue 11, pages 461-463, November 1999; “High Efficiency Monolithic Gallium Nitride Distributed Amplifier”, Green, et al., IEEE Microwave and Guided Wave Letters, Vol. 10, Issue 7, pages 270-272, July 2000; “Experimental Performance of Ultra Broadband Amplifier Design Concept Employing Cascaded Reactively Terminated Single Distributed Amplifier Configuration”, Virdee, et al., Electronic Letters, Vol. 36, Issue 18, Pages 1554-1556, Aug. 31, 2000; and “Analysis of the Performance of Four Cascaded Single Stage Distributed Amplifiers”, by Banyamin, et al, IEEE Transactions on Microwave Theory and Techniques, Vol. 48, Issue 12, Pages 2657-2653, December 2000.
Low noise wide band amplifiers are normally formed from Type III-IV semiconductors, such as GaAs and InP semiconductors, formed into one or more high electron mobility transistor (HEMT) or heterojunction bipolar transistor (HBT) gain cells for such distributed amplifiers. Examples of such low noise wide band amplifiers are disclosed in U.S. Pat. Nos. 5,710,523 and 5,838,031. Such low noise wide band amplifiers are also disclosed in: “6 to 18-GHz Two Stage Distributed Low Noise Amplifier Pesion For High Yield”, Culver et al, Twelfth Annual Gallium Arsenide Integrated Circuit (GaAs Ic) Symposium, 1990 Technical Digest, Pages 301-304, Oct. 7-10, 1990; “Ultra High Gain, Low Noise Monolithic InP HEMT Distributed Amplifier from 5-40 GHz”, Electronic Letters, Vol. 26, Issue 8, Pages 515-516, April 1990; “2-18 GHz GaAs Monolithic Ultra Broadband Amplifier”, by Lingli et al, 1998 International Conference on Microwave and Millimeter Wave Technology Proceeding. ICMMT '98, pages 238-241, Aug. 18-20, 1998. “Ka-Band Multi Stage MMIC Low Noise Amplifier Using Source Inductors with Different Values for Each Stage”, Uchida, et al, IEEE Microwave Guided Wave Letters, Vol. 9, Issue 2, Pages 71-72, Feb. 19, 1999.
Many known distributed amplifiers are known to include reactive matching elements, such as inductors and capacitors. Such inductors and capacitors are many times larger than the active transistor amplifying device, causing the amplifier layout to be relatively large. Moreover, reactively matched amplifiers are known to have a limited bandwidth, for example, 10%-20% bandwidth, because at each discrete frequency point across the amplifier bandwidth, a different value reactive element is needed to cancel out the reactive impedance portion of the active device itself. Moreover, such reactive matching elements are known to include a resistive component which adds to input losses in the amplifier and cause degradation in the noise performance in the amplifier.
In order to overcome these disadvantages, direct coupled amplifiers with active input matching have been developed, for example, as disclosed in; “A Monolithic HEMT-HBT Direct Coupled Amplifier with Arrive Input Matching”, by Kobsyashi, e1 at. IEEE Microwave and Guided Letters, vol. 6, no. 1, pages 55-57, January 1996. In this application a common gate HEMT is used for arrive impedance matching of a URT amplifier configured as a Darlington pair. In this application, the common gate HEMT is directly coupled to the HBT amplifler. Thus, a wide band low noise amplifier is needed which provides relatively lower noise figure performance and ax the same time reduces the layout size of the amplifier relative to known wide band amplifiers.